Congenital heart block (CHB) is present at or before birth and impairs the heart's electrical signalling from the upper to the lower chambers. CHB carries a 20 percent death rate and nearly all survivors require pacemakers. Joshua Copel, M.D., professor in the Department of Obstetrics, Gynecology & Reproductive Sciences at Yale conducted the study to evaluate an early marker of cardiac injury before there is permanent scarring.

The group conducted a longitudinal observational study following over 100 women with the anti-Ro and anti-La antibodies to determine if there were early signs of foetal heart problems. They also explored whether early treatment would reverse the problems.

The team found that while first-degree foetal heart block may be reversible with the steroid drug dexamethasone, the condition could advance within as little as one week to a third-degree block, which is irreversible even with further intervention.

"Given the high recurrence rate we confirmed in this study, close monitoring and the earliest possible marker is necessary," said Copel, who plans trials of other possible treatments. "Advanced block and permanent heart damage can occur within one week of a normal echocardiogram, even a weekly evaluation may not be sufficient to detect early onset of disease."